CHICAGO — In a season filled with injuries, the Chicago Cubs have their Cubbie Occurrence. A freak incident for Matthew Boyd on Wednesday morning led to a meniscus injury that will keep the left-handed starter out indefinitely.

“Just going down onto the ground and getting back up,” manager Craig Counsell said of how the injury occurred. “Kind of unexplainable. Sitting down on the ground with his kids.”

Counsell said the extent of the injury wouldn’t be known until Boyd underwent surgery, which had yet to be scheduled. Boyd had only just returned from getting the MRI hours before first pitch Wednesday.

This is already Boyd’s second stint on the injured list (left biceps strain), and he becomes the 10th pitcher on the Cubs’ 40-man roster on the shelf. Cade Horton is already lost for the season after undergoing elbow surgery. Late last month, Justin Steele suffered a setback while rehabbing from last summer’s elbow surgery. He’ll be re-evaluated in about three weeks to determine whether he can start his throwing program back up, but he’s not expected back until after the All-Star break.

One team source said the Cubs are still hoping for the best with Boyd. That would still be around six weeks for this type of injury. A more significant meniscus injury can result in months of missed time. Counsell said the expectation is that Boyd will pitch again this season.

“Obviously, it’s unexpected news,” Counsell said. “We’re gonna have to fill in around him for sure. That’s going to be our task.”

With Boyd headed to the IL, the Cubs added veteran right-handed reliever Trent Thornton to the roster and designated Charlie Barnes for assignment.

Javier Assad, working out of the bullpen, could shift back into the rotation, but Counsell said that hadn’t been decided yet. Beyond that, the Cubs’ starting pitching depth has been greatly weakened. What was once viewed as a strength entering the season has quickly evaporated.

Jordan Wicks, who started the season on the IL, is rehabbing at Triple A. He has a 9.53 ERA over four starts (11 1/3 innings) and doesn’t appear to be a viable option at this time. Veteran Kyle Wright, signed as a non-roster invitee over the winter, was working his way back from multiple injuries and threw four innings Friday in Arizona. Wright was up to 96 mph and was set to head to Iowa to get in-game action, but he suffered a setback when he felt pain in his shoulder again over the weekend.

Vince Velasquez, who was designated for assignment April 26 after a brief call-up, rejoined the organization Monday and was assigned to Triple A. Top pitching prospect Jaxon Wiggins hasn’t thrown in a game since April 4 and is on the IL with right elbow inflammation. However, he’s looked good in recent bullpens and is scheduled to throw a live BP on Friday in Arizona.

Ben Brown has been brilliant out of the bullpen, giving the team a 2.10 ERA in 25 2/3 innings spread out over 12 appearances. He’s gotten more than three outs in all but one of his outings and has become a critical part of a bullpen that’s suffered significant injuries as well. It’s unlikely his role will change in the immediate future, but it will be a topic of discussion with so many injuries to the rotation.

As the Cubs search for reinforcements, Assad and Colin Rea will have to step up. Shota Imanaga has had a brilliant bounce-back season thus far with a 2.40 ERA in seven starts. Jameson Taillon is missing more bats than ever in a Cubs uniform and has kept the team in games more often than not. Edward Cabrera seems to have found a rhythm on the mound and is consistently giving the team quality starts.

Ultimately, the Cubs might have to look outside the organization to get help. Adding pitching at the trade deadline becomes all the more imperative for a team that’s proven to be impressively resilient as the injuries pile up. One thing is for sure, Counsell and his team won’t dwell on what’s already happened and feel sorry for themselves.

“There’s no benefit to doing that,” Counsell said. “This is an opportunity for somebody. Through those opportunities, good things can happen. That’s how you have to see it.”